Anionic Synthesis of Chain-End and In-Chain, Cyano-Functionalized Polystyrenes by Hydrosilylation of Allyl Cyanide with Silyl Hydride-Functionalized Polystyrenes

ω-Cyano-functionalized polystyrene has been prepared in 87% isolated yield using the general functionalization methodology based on anionic polymerization, silyl hydride functionalization, and hydrosilylation with allyl cyanide. First, an ω-silyl hydride-functionalized polystyrene was prepared quantitatively from poly(styryl)lithium by reaction with dimethylchlorosilane in hydrocarbon solution. Then the silyl hydride-functionalized polystyrene was added to allyl cyanide using Karstedt’s Pt(0) hydrosilylation catalyst. This general functionalization methodology was also used to develop a new synthesis of in-chain functionalized polymers. First, an in-chain, silyl hydride-functionalized polystyrene was prepared quantitatively from the reaction of excess poly(styryl)lithium with dichloromethylsilane in hydrocarbon solution. The excess poly(styryl)lithium was reacted with ethylene oxide to form an easily separable, hydroxyl-functionalized polystyrene. Then the purified, in-chain silyl hydride-functionalized polystyrene was added to allyl cyanide using Karstedt’s Pt(0) hydrosilylation catalyst. The resulting in-chain, cyano-substituted polystyrene was isolated in 58% yield. The silyl hydride- and cyano-functionalized polystyrenes were characterized by SEC, FTIR, 1H and 13C NMR, and MALDI-TOF mass spectrometry.